Who is John Galt?

"He said he would stop the motor of the world... and he did. But who is John Galt? A destroyer, or a liberator? Why does he fight his battle, not against his enemies, but against those who need him most? Why does he fight his hardest battle against the woman he loves?" No, sorry, I'm thinking of Joe Buck.

From the Village Voice, by way of Alicublog, Incredibly Strange Bloggers go all John Galt on us.